Show don't tell is very important, after all, it's a comic and not an illustrated novel. However, if push comes to shove and you do need to introduce the readers to lore, break it up as much as possible - have interesting things happening on the panels or make the characters discuss or show their personality through it, don't sit everyone down for a lecture which might be as boring to them as it is to who's reading. And if it's not all essential right now, look through your notes to see what can be pushed to a later date. I don't actually talk about my comic's world's "origin" until chapter 2, for example, and even then it's just enough so people know the character's struggles - tidbits and hints come through the rest of the dialogue or visual storytelling, or even Extras episodes if it's for the very curious ones and doesn't affect the plot.
And no walls of text, imho. Even if your exposition is several paragraphs, break up the text so it's four lines per bubble (or rectangle, or nothing) as it can easily bore someone who's trying to understand all of it and look at the art together. An actual good use of wall of text is if a character is blabbering away in the background of another scene or the focus character isn't paying attention to their speech, and it's optional for the reader to actually try to decipher that or not.